Photosensitivity first
Every visit starts with a warning, and nothing changes color until you press Start. Flashing light can trigger seizures in people with photosensitive epilepsy. The web’s accessibility rules allow no more than three flashes in any one second (W3C, WCAG 2.3.1), and W3C notes that people are even more sensitive to red flashing. So every mode here is capped at 3 flashes a second, saturated red never flashes, Fade comes first, and a device set to reduce motion starts in a slow fade. If anyone present has photosensitive epilepsy, use Fade only or don’t use the page. No flashing light can be called safe for everyone; this warning is a safety notice, not medical advice.
How to use the disco light
- Read the warning and press Start, or Go back to keep the screen dark.
- Pick Fade, Party or Strobe.
- In Party, press Tap on the beat of your music.
- Press Fullscreen or F for a full-screen light.
- Press Stop or Esc to end; Space pauses and resumes.
Fade, Party and Strobe modes
Fade turns smoothly through the color wheel, once every 10 seconds by default (4–30 s), with no flashes. Party makes one hard color change per beat, from 30 to 180 BPM; the default 120 BPM is two changes a second, and it never shows the same color twice in a row. Strobe switches on and off from 0.5 to 3 times a second (2 by default). With Soft strobe on, the off state is 30 % of the color instead of black, which is less harsh in a dark room. Strobe color is White, or Palette to take the next palette color on each flash.
Set the tempo with Tap
Press Tap or T four times on the beat. The tempo becomes the average of your last four taps, between 30 and 180 BPM, and a pause of more than 2 seconds starts the count again. The page never listens through your microphone, so the beat is always yours.
Party set-ups: TV, laptop and several phones
A TV in a dark room makes the biggest light; lower its brightness a little so it doesn’t glare. A laptop facing a pale wall spreads the color across the room. Several phones on different palettes around a table look like a light show. Keep the screens on and plugged in, and never use it in a moving car. For party games between songs, add a bomb timer or a random timer.
Options explained
Mode starts on Fade. Fade cycle is 10 s, Tempo (BPM) 120 and Strobe rate 2 Hz. Soft strobe is on and Strobe color is White. Palette offers Rainbow (the default), Neon, Warm, Cool and Custom with up to six hex colors. Brightness runs from 5 to 100 %. With reduced motion, the warning adds Allow flashing anyway; Keep screen on is in Settings.
How it works
This is an online disco light that runs on your screen: the browser paints a new color on each frame, at most 30 times a second while fading. Party picks each next color with your browser’s cryptographic random numbers. Before any color change, a counter compares it with the flash definition the accessibility rules use and skips a change that would make a fourth flash within a second. A separate check keeps saturated red out of the flashing modes. The page makes no sound at all.
Tips and limits
- A screen is far dimmer than stage lights; darken the room for the best effect.
- In daylight outdoors it is barely visible.
- Full brightness for hours drains batteries, so plug in.
- For one steady color instead, use the pink screen; for calm white light after the party, the screen light.
FAQ
Can disco lights cause seizures?
Yes, for some people with photosensitive epilepsy, flashing light can trigger a seizure. This page shows a warning first, never flashes more than 3 times in any second, never flashes saturated red and starts in the slow Fade mode. If anyone present is sensitive to flashing light, use Fade only, or skip it.
How fast can this disco light flash?
At most 3 flashes in any one second, in every mode. Party tops out at 180 BPM, which is 3 color changes a second, and Strobe at 3 on-off flashes a second. A counter checks every color change against that limit and drops any change that would go over it.
Can the disco light react to music?
Not by listening: the page never uses your microphone. Instead, press Tap or T four times on the beat of whatever is playing and Party changes color on that tempo. Your music stays private, and the light stays in time as long as the song keeps a steady beat.
How do I make a disco light with my phone or TV?
Open this page on the device, read the warning and press Start. Choose Party and press Fullscreen. On a TV, use its web browser or cast a browser tab to it. Turn the room lights down and point the screen at a pale wall for a bigger, softer glow.
What colors do disco lights use?
Mostly the rainbow: orange, yellow, green, cyan, blue, violet and pink, which is the Rainbow palette here. Neon is brighter and punchier, Warm sticks to oranges and corals, and Cool to blues and teals. With Custom you can type up to six hex colors of your own.
Can I use several phones or screens at once?
Yes. Each device runs on its own, so open the page on every phone, tablet or laptop and press Start on each. Different palettes on different screens look best around a room. Plug them in, and keep Keep screen on switched on in Settings.
Why can't red flash in Party or Strobe mode?
Because people are even more sensitive to flashing saturated red than to other colors, as W3C notes in its guidance on flashing content. So saturated reds are dropped from Party and Strobe, and choosing one shows a short message. Red is still part of the slow Fade mode.
Do disco lights work outside?
A screen is far too dim to show color in daylight, so outdoors it only works after dark. On a balcony or in a garden at night, a laptop or TV in Fade or Party gives a gentle glow. Keep devices out of rain and dew.
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